Forget the capes. This hero wears a robe.

U.S. Supreme Court Justice Ruth Bader Ginsburg reacts to the audience while being introduced before a discussion about Roe V. Wade at the University of Chicago Law School in 2013.

U.S. Supreme Court Justice Ruth Bader Ginsburg reacts to the audience while being introduced before a discussion about Roe V. Wade at the University of Chicago Law School in 2013.

(John J. Kim, Chicago Tribune)

Ann HornadayWashington Post

While "Avengers: Infinity War" breaks box office records, "Deadpool 2," the snarkily self-referential anti-superhero comedy starring Ryan Reynolds, threatens its strait-laced cousin's throne this weekend. Meanwhile, "Solo: A Star Wars Story" waits in the wings, hoping that the original tale of late 20th-century cinema's most beloved curmudgeon can prove that the creaky franchise can still put tushies in seats.

But as the official summer movie season gets underway in earnest, it's quite possible that each of these boys-and-their-toys adventures will be outperformed - at least proportionately - by a little documentary that is emerging as an early sleeper hit.

"RBG," an absorbing, endearing film about Supreme Court associate justice Ruth Bader Ginsburg, is punching far above its weight at the box office, becoming just as much an unexpected phenom as its subject. Last week, the CNN-produced film, by Julie Cohen and Betsy West, managed to earn a spot on the top 10 best-performing movies, earning more than $1 million at the box office and bringing its current total to more than $2 million. "It's almost unheard of to see a [documentary] perform this well in summer blockbuster season," Exhibitor Relations analyst Jeff Bock told Variety's Rebecca Rubin. "For the documentaries to hit $1 million, it's like a regular film hitting $100 million."

The subtitle for that Variety article, by the way, was "How Ruth Bader Ginsburg Became a Summer Box Office Avenger" - entirely in keeping with the venerated jurist's late-blooming career as pop culture icon and ubiquitous meme. While the boys of summer out-blast, out-quip and out-cool each other in desperate attempts to create and elaborate on their fictional legends, Ginsburg is proving that real-life legends need no posturing, preening or pyrotechnics to earn their cred. A few lace collars and bicep curls will suffice.

The reasons for "RBG's" success are no doubt historically and culturally specific: In an era of weaponized partisan rancor, the diminutive, fiercely resilient Ginsburg is that rare transcendent figure who personifies personal integrity and grace. (Her longtime friendship with ideological rival Antonin Scalia is celebrated in the film.) And she's part of a generation of women - including Madeleine Albright, Elizabeth Warren, the late Barbara Bush and Maxine Waters - who are being rediscovered by millennials and Gen-Zers as avatars of candor, principle and steadfastness worthy of admiration, whether by way of tattoos (Ginsburg has inspired a few) or viral hashtags.

That's no doubt why "RBG" proved such a hit over Mother's Day weekend, as older women, their daughter and granddaughters flocked to their local art houses to cheer Ginsburg on as she pursued a law career - with the enthusiastic support of her husband, Marty. "RBG" isn't just a Wiki-list of accomplishments, although Ginsburg's germinal work in feminist civil rights law is utterly fascinating (and heretofore largely unknown, thanks to her famous shyness). It's also the love story of soul mates whose relationship exemplified the kind of marriage in which passion, humor, equal respect and mutual devotion exist in balance worthy envying - and emulating.

"RBG" will open in even more theaters this weekend, alongside "Book Club," a comedy starring Diane Keaton, Jane Fonda and Candice Bergen that feels reverse-engineered to appeal to the exact same demographic that made "RBG" such a smash hit. Ginsburg is even referenced in "Book Club," as the name of the cat belonging to Bergen's character, a federal judge. But, at least in documentary form, she's worthy of more than a playful homage: "RBG" is experiencing the kind of commercial success that "Book Club" is counting on, the same appeal to women (and their daughters) that made "Mamma Mia!," "The Best Exotic Marigold Hotel" and countless Nancy Meyers rom-coms big hits, along with smaller but impressively profitable indies such as "The Woman in Gold," "Hello, My Name is Doris," "I'll See You In My Dreams," and "Grandma."

If "Book Club" does well this weekend - and from the audience reaction at this week's previews, it has a strong chance of doing so - there will inevitably follow the conclusion that it "overperformed," meaning that it exceeded the expectations of studio executives, prognosticators and sundry self-described "experts." What that constituency rarely admits is that, once again, it's they who chronically underestimate female filmgoers, especially when they're older than 25. It's the business-side corollary of the same tunnel vision we've seen in the wake of the Harvey Weinstein scandal, wherein women are prized in Hollywood primarily as young, pliable sex objects and pulchritudinous foils rather than as fully realized humans with compelling quests and journeys of our own.

Just as the movie industry reflexively discards women as worth desiring or even considering once we reach middle age, it similarly ignores us as a lucrative and powerful market - even though older women reliably turn out to see movies and, perhaps even more importantly, tell their husbands what they should see over the weekend.

The male gaze that still largely defines and decides what Hollywood is interested in might render women invisible, but it's to the industry's detriment. Films like "RBG" and, quite possibly, "Book Club," will continue to prove how self-defeating sexist myopia can be. Nevertheless, women will persist, as we so often do. All the way to the bank.